Pic16f1825 adcon0

Hi,
i'm using PIC16F1825 for the first time and want to use RC2 as analog input.
Therefore i want to use the internal voltage reference (4.096V).
I set the FVRCON = %10000011.
But there is an item in the ADCON0 that i don't understand...
I think i have to use ADCON0 = %00011001 for using analog channel 6?
But what means (bit6-2) "11111 = FVR (Fixed Voltage Reference) Buffer 1 Output?
What is this for?
Must i use this for my reference voltage?

Thanks in advance
best regards
norbert

Hi Norbert,

I used the PIC16F1825 in a recent project with ADC input on AN0.
I used FRVCON = %11010011 to enable the fixed voltage reference and set the voltage to 4.096V.
Your ADCON0 = %000110001 is correct for selecting AN6 as the ADC channel (RC2).
To apply the fixed voltage reference to the ADC you must set bit 1-0 of ADCON1 to "11"
In my application I used ADCON1 = %10100011 to right justify the output, set A/D clock to Fosc/32 and set Vref- to VSS.
You may need to change the A/D clock selection depending on you own oscillator choice.

Cheers
Barry
VK2XBP

Hi,

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But what means (bit6-2) "11111 = FVR (Fixed Voltage Reference) Buffer 1 Output?[

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It simply selects the output of the FVR and "connects it" to the ADC input in order to sample it, just as any other input.

Quote:

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What is this for?

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It can be used to "calibrate" the ADC when you're not actually using the FVR as VRef for the ADC.

Quote:

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Must i use this for my reference voltage?

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No, in your case, with the output of the FVR used as VRef for the ADC there's no need to sample the FVR output - it would/should Always return a result of 1023.

/Henrik.

Hello Barry / Henrik,
thanks for reply, it helped me understanding this function.
I did my settings this way - everything's fine.
Thanks for help.
Norbert